ABSTRACT The overall objective of this proposal is to improve the quality of life of female Veteran patient population. Recent surveys indicate that the female patient population constitutes the fastest growing segment of VA health care users and pelvic floor disorders (fecal and urinary incontinence, pelvic organ prolapse) are extremely common in this patient population. Fecal incontinence is reported approximately, 7-10% of women over the age of 60. Child birth related injury/ trauma to external anal sphincter injury (EAS) is attributed as the most common cause of fecal incontinence. The most commonly performed surgical procedure for the treatment of fecal incontinence is overlapping sphincteroplasty and long term follow up studies show a poor success rate with this surgical correction. We plan to use an animal model to study the length tension properties of the EAS, and then perform a series of experiments to show that this knowledge can be used to enhance anal canal pressure and continence function. Our preliminary data show that the in-vivo operational EAS muscle sarcomere length is much smaller than its optimal length and it is possible to gain EAS muscle function by increasing the EAS sarcomere length. The specific goals of our study are: 1) To determine the effects of surgical plication of the EAS on the EAS sarcomere length and the anal canal pressure in-vivo in an animal model (rabbit). We will also determine the long-term effects of EAS plication on the durability of gain in the EAS muscle function. 2) We will also study the following to understand why sphincteroplasty operation does not provide the long lasting effects. The goals of these studies in our animal model (rabbit) will be to determine: a) The effects of the EAS myotomy on the development of fecal incontinence. b) The effect of EAS myotomy on the sarcomere length c) The effects of sphincteroplasty with varying degrees of overlap on the EAS muscle function. 3) The length tension relationship of the EAS muscle in the humans to show that the length tension properties of the rabbit and humans are similar. PUBLIC HEALTH RELEVANCE: The overall objective of this proposal is to improve the quality of life of the female Veteran patient population. The expansion of women in the military is reshaping the veteran population, with women now constituting the fastest growing segment of eligible VA health care users. In recognition of the health care needs of women, the VA Office of Research &Development sponsored the first national VA Women's Health Research Agenda-setting conference to map research priorities to the needs of women veterans in 2004. Urinary and fecal incontinence affect large number of women (up to 20% or more). Therefore, the fundamental and translational research into fecal continence and incontinence is of utmost importance to the women in military and eligible VA health care users. Fecal incontinence is a major medical illness, especially in women because of the birth related injury to the anal sphincters. The goals of our study are to improve our understanding of the physiology of anal sphincter muscles. We propose that the new information will lead to better medical and surgical treatment strategies in the treatment of fecal incontinence. The physiological principles discussed in this proposal are quite likely to be applicable to urinary continence and incontinence function. Our observations suggest that just like external anal sphincter, the other sphincter muscles, including the ones involved in urinary continence, share similar physiological principles as discussed in this proposal.